Ruggedized typebar guide

ABSTRACT

A ruggedized typebar guide is disclosed comprising two spaced pivots and two guide dogs rotatably mounted to the pivots with each guide dog having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path. Shock absorbing means are provided permitting limited movement of the pivots in a direction substantially parallel the flight path upon rotation of the guide dogs. Means are also provided for rotating the guide dogs about the movable pivots upon passage of a typebar between the guide dogs along the typebar flight path to converge the two opposing cam surfaces towards one another a predetermined distance within the flight path to center the typebar.

[451 Apr. 24, 1973 3,645,374 2/1972 Allen....,.............................197/43X Primary Examiner-Emest T. Wright, J r. Altorney-Robert B. Kennedy and Milton M. Wolson [57] ABSTRACT A ruggedized typebar guide is disclosed comprising two spaced pivots and two guide dogs rotatably mounted to the pivots with each guide dog having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path. Shock absorbing means are provided permitting limited movement of the pivots in a direction substantially parallel the flight path upon rotation of the guide dogs. Means are also provided for rotating the guide dogs about the movable pivots upon passage of a United States Patent 1 Mueller i 1 RUGGEDIZED TYPEBAR GUIDE [75] lnventor: Hans W. Mueller, Cortland, NY,

[73] Assignee: SCM Corporation [22] Filed: June 1, I971 [21] Appl. No.: 148,457

[52] US. [51] Int. 25/22 [58] Field of Search.................................197/43, 183

[56] References Cited UNlTED STATES PATENTS 97/43 typebar between the guide dogs along the typebar 197/43 flight path to converge the two opposing cam surfaces ....197/43 towards one another a predetermined distance within 197/43 the flight path to center the typebar. ......l97/183 197/ l 8 3 X l 1 Claims, 2 Drawing Figures 900 Anderson...........

Smith........ Alexander Pfau Ursbruck... Mil1er........ Zeamer..... Ryan et al.....

Patented April 24, 1973 3,729,080

INVENTOR HANS W. MU ELLER 1 RUGGEDIZED TYPEBAR cums BACKGROUND OF THE INVENTION This invention relates generally to typewriters, and particularly to means for guiding typebars as they approach a typewriter platen for printing, and for repulsingtypebars away from the platen after the printingoperation has been performed.

I-Ieretofor, the prevalent means employed for guiding individual typebars from their stayed position to their print position within a printing station at the platen has comprised a segmented base plate into which the typebars are pivotally mounted at their base. Two spaced type guides having confronting arcuate surfaces are also mounted adjacent the typewriter platen and printing station for final alignment just prior to typebar impact with the platen, In operation, an individual typebar pivots at its base and is guided by the sides of the slot into which it tits in the segmented base plate. As it approaches the platen it also passes between incident lips of the two spaced type guides. If properly centered the typebar clears the confronting arcuate guide surfaces and strikes the platen or paper thereon; but if slightly off-center the typebar strikes one of the arcuate guide surfaces and is deflected towards the center of the flight path. The terminal portion of the flight paths of the upper portion of each typebar ad- "jacent the type head which portion passes between the two spaced guides adjacent the platen are substantially coincident. The flight paths of the remaining, lower portion of the typebars are diverse as also are those of the upper portions during their initial approach to the guides from their stayed positions. I

Use of the just described fixed typebar guides adjacent the platen has given rise to several technical problems which have in turn led to an impairment of the quality of the machine print in the form of lack of character clarity, non-uniformity of print impact, and low lateral tolerance in character location on the surface of the imprintable medium. For example, typebars which are properly aligned pass through the guides without striking their arcuate surfaces and thus strike the platen or paper thereon with greater force than do those which are slightly misaligned and strike one or more of the arcuate surfaces of the rigid guides adjacent the platen. The spacing between the guides must also be substantial, such as to leave one or two mils clearance with the typebar, in order to prevent pronounced typebar deceleration and vibration from occuring as a misaligned typebar first strikes one guide surface, rebounds to another, and so forth. This excess spacing is productive of'lateral imprecision in print location and, in severe cases, of even a blurring of print as the character font on t he typehead strikes the paper at an angle to the platen normal. In addition, the passive guide means of the prior art have not driven typebars back towards their stayed position after their print operation has been effected at the platen. Consequently, the typebars have lingered somewhat in contact with the platen which contact interval has lessened the degree of sharpness of the printed characters. Moreover, the typebars themselves have had to beprehardened to withstand the severe wear produced by continuous striking of the rigid guides over prolonged periods of time/Such prehardening has, of course, produced added costs.

Accordingly, it is a general object of the present invention to provide an improved, ruggedized typebar guide.

More specifically, it is an object of the present invention to provide ruggedized means for guiding typebars as they approach a typewriter platen which does not significantly impair print quality.

Another object of the invention is to provide ruggedized means for guiding typebars into a print station without inducing significant vibrations in the typebars.

Another object of the invention is to provide a typebar guide with which un-prehardened typebars may be used over long periods of time.

Yet another object of the invention is to provide a ruggedized typebar guide having self-contained shock absorbing means.

Another object of the invention is to provide a ruggedized typebar guide which upon print operation drives the guided type-bars away from the type-writer platen towards their stayed positions thereby reducing the time interval during which the type is in printing contact with the typewriter platen or imprintable medium thereon.

SUMMARY OF THE INVENTION Briefly described, the present invention is a ruggedized typebar guide comprising two spaced pivots and two guide dogs rotatably mounted to the pivots and having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path. Shock absorbing means are provided permitting limited movement of the pivots in a direction substantially parallel the flight path upon rotation of the guide dogs. Means are also provided for rotating the guide dogs about the movable pivots upon passage of'a typebar between the guide dogs along the typebar flight path to converge the two opposing cam surfaces towards one another a predetermined distance within the flight path to center the typebar.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a ruggedized typebar guide incorporating principles of the present invention.

FIG. 2 is aperspective view of the ruggedized typebar guide shown in FIG. 1 in the process of guiding a typebar towards a platen for printing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in more detail to the drawing there is shown in FIG. 1 a ruggedized typebar guide comprising a bifurcated frame 10 having two spaced, coplanar horizontal extensions 12 on which are respectively mounted two cantilevered leaf springs 14 by screws 16. Each leaf spring 14 has a bifurcated U-shaped end portion 18 in which reside pivots 20. Two guide dogs 22 are rotatably mounted on pivots 20 between the bifurcated U-shaped end portions 18 of cantilevered leaf springs 14. In the position shown cam surfaces 25 of guide dogs 22 are disposed adjacent opposite sides of typebar flight path 26 while actuating lug end portions 28 of the guide dogs 22 overlap one another within the flight path 26. The opposite ends 32 of the guide dogs 22 serve as stop lugs as their movement is limited by leaf springs 14. Finally, torsion springs 34 are mounted about pivots with one end thereof spring biased against Horizontal Frame Extension 12 and the other against guide dogs 22.

In operation, as a typebar 35 approaches the guide along typebar flight path 26 it passes within the flight path 26 between confronting cam surfaces of guide dogs 22 and then strikes guide dog actuating lugs 28. The momentum of the typebar 35 causes it to continue moving towards platen within the flight path 26, which path 26 extends normally therefrom, till it is in the position illustrated in FIG. 2 with font 36 on typebar head 38 in printing contact with the platen 30. This movement against actuating lug portions 28 causes them and guide dogs 22 integral therewith to rotate about pivots 20 thereby twisting torsion springs 34. The impact of typebar on actuating lug portions 28 also causes the guide dogs 22 to exert a reactive force on pivots 20 in a direction parallel to flight path 26 away from platen 30. This is due to the fact that the point of guide dog contact with the pivots 20 is remote from the guide dog center of percussion. As the pivots 20 are sandwiched between horizontal frame extensions 12 and resilient cantilevered leaf springs 14 they themselves move slightly in the just-mentioned direction thereby serving to absorb the reactive shock which would otherwise occur were pivots 20 not permitted such slight motion. The force of springs 14 quickly overcomes the reactive force created by the impact of typebar 35 on the guide dogs 22 causing pivots 20 to return to their original positions.

As guide dogs 22 rotate their confronting cam surfaces 25 laterally converge towards one another. Should typebar 35 not be aligned along the center of the typebar flight path 26 it will be pushed by one of the converging cam surfaces 25 of the guide dogs 22 towards that center thereby properly aligning it. After striking the platen 30, which action arrests the forward motion of the typebar actuating lug portions 28, the guide dogs 22 spring biased by torsion springs 34 propel typebar 35 and typebar head 38 attached thereto away from the platen 30. Guide dogs 22 in turn pivot until their stop lug portions 32 strike leaf springs 14. By this action cam surfaces 25 are laterally diverged back to their initial position as depicted in FIG. 1.

It should be understood that the just-described embodiments are merely illustrative of principles of the invention, and that many modifications may be made thereto without departure from the spirit and scope of the invention as set forth in the following claims.

l claim 1. A ruggedized typebar guide comprising:

two spaced pivots;

two guide dogs rotatably mounted on said pivots and having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path;

shock absorbing means mounting said pivots for limited movement in a direction substantially parallel said flight path upon rotation of said guide dogs; and

means for rotating said guide dogs about said movable pivots upon passage of a typebar between said guide do s along said type-bar flight path to con- I verge sai two OPPOSlng cam surfaces towards one another a predetermined distance within said flight path to center said typebar.

2. A typebar guide in accordance with claim 1 wherein said shock absorbing means includes means mounting said pivots for reciprocal movement in said direction.

3. A typebar guide in accordance with claim 1 wherein said shock absorbing means includes a spring.

4. A typebar guide in accordance with claim 3 wherein said springs are cantilevered.

5. A typebar guide in accordance with claim 3 wherein said springs are in contact with said pivots.

6. A typebar guide in accordance with claim 1 including means for diverging said two opposing cam surfaces away from one another out of said flight path and for simultaneously ejecting said typebar out from between said guide dogs.

7. A typebar guide comprising:

a bifurcated frame;

two spaced leaf springs cantilevered on said bifurcated frame;

two pivots mounted on said two spaced leaf springs respectively; two guide dogs rotatably mounted on said two pivots,

respectively, and having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path; and

means for rotating said guide dogs about said pivots upon passage of a typebar between said guide dogs along said typebar flight path to converge said two opposing cam surfaces towards one another a predetermined distance within said flight path to center said typebar.

8. A typebar guide in accordance with claim 7 including means for diverging said two opposing cam surfaces away from one another out of said flight path and for simultaneously ejecting said typebar out from between said guide dogs.

9. A typebar guide in accordance with claim 7 wherein said leaf springs define spring apertures, and wherein a first portion of said guide dogs is rotatably mounted within said apertures.

10. A typebar guide in accordance with claim 9 wherein a second portion of said guide dogs located adjacent said first portion is mounted for contact with said leaf springs upon rotation of said guide dogs to thereby serve as a guide dog stop lug.

11. A typebar guide in accordance with claim 10 comprising two torsion springs connected to said guide dogs to spring bias said guide dog second portions against said leaf springs. 

1. A ruggedized typebar guide comprising: two spaced pivots; two guide dogs rotatably mounted on said pivots and having spaced opposing cam surfaces respectively disposed along opposing sides of a typebar flight path; shock absorbing means mounting said pivots for limited movement in a direction substantially parallel said flight path upon rotation of said guide dogs; and means for rotating said guide dogs about said movable pivots upon passage of a typebar between said guide dogs along said type-bar flight path to converge said two opposing cam surfaces towards one another a predetermined distance within said flight path to center said typebar.
 2. A typebar guide in accordance with claim 1 wherein said shock absorbing means includes means mounting said pivots for reciprocal movement in said direction.
 3. A typebar guide in accordance with claim 1 wherein said shock absorbing means includes a spring.
 4. A typebar guide in accordance with claim 3 wherein said springs are cantilevered.
 5. A typebar guide in accordance with claim 3 wherein said springs are in contact with said pivots.
 6. A typebar guide in accordance with claim 1 including means for diverging said two opposing cam surfaces away from one another out of said flight path and for simultaneously ejecting said typebar out from between said guide dogs.
 7. A typebar guide comprising: a bifurcated frame; two spaced leaf springs cantilevered on said bifurcated frame; two pivots mounted on said two spaced leaf springs respectively; two guide dogs rotatably mounted on said two pivots, respectively, and having spaced opposing cam surfaces respectively disposed aloNg opposing sides of a typebar flight path; and means for rotating said guide dogs about said pivots upon passage of a typebar between said guide dogs along said typebar flight path to converge said two opposing cam surfaces towards one another a predetermined distance within said flight path to center said typebar.
 8. A typebar guide in accordance with claim 7 including means for diverging said two opposing cam surfaces away from one another out of said flight path and for simultaneously ejecting said typebar out from between said guide dogs.
 9. A typebar guide in accordance with claim 7 wherein said leaf springs define spring apertures, and wherein a first portion of said guide dogs is rotatably mounted within said apertures.
 10. A typebar guide in accordance with claim 9 wherein a second portion of said guide dogs located adjacent said first portion is mounted for contact with said leaf springs upon rotation of said guide dogs to thereby serve as a guide dog stop lug.
 11. A typebar guide in accordance with claim 10 comprising two torsion springs connected to said guide dogs to spring bias said guide dog second portions against said leaf springs. 